When fabricating ring lasers, it is desirable to attach a metal cathode and one or more metal anodes to a glass or to a glass-ceramic material such as those known by the trademarks of "Zerodur" or "Cervit."
Typically the cathode or anode is aluminum or copper, although the method of this invention could be used to attach other metals such as, for example, iron, steel, nickel, tantalum, or niobium to glass or glass-ceramic material.
The details herein pertain specifically to aluminum and copper.
The closest prior art known to the applicants is that described in United Kingdom Pat. No. 687,259 to The British Thomson-Houston Company Limited, which describes a glass-to-metal seal using a silver plating over the base metal and an indium plating over the silver, then casting molten glass into contact with an indium plated portion of the metal member. Another prior art patent of interest is U.S. Pat. No. 3,777,281 which pertains to the use of gold and indium in forming a ceramic-to-ceramic seal.
Prior to this invention, gold in a liquid was painted onto both the glass and metal parts, and the parts were fired to leave just the gold. Next an indium wire was positioned between the two gold surfaces, and the indium was melted to solder the two gold surfaces together. The procedure was found to be unreliable, and many gas leaks were detected.